Displacement machines of the spiral type are known for instance from U.S. Pat. No. 3,989,422. A compressor designed on this principle operates by virtually pulsation-free feeding of the gaseous operating medium, for instance air or an air/fuel mixture, and can, therefore, be advantageously used for charging internal combustion engines, as well as other purposes.
During the operation of such a compressor in accordance with a first embodiment, a plurality of approximately crescent-shaped work chambers are enclosed along a stationary feed chamber between the spiral, orbiting displacement bodies and the two peripheral walls of the feed chamber. These work chambers move from the inlet through the feed chamber to the outlet, in the course of which their volume is decreased continuously and the pressure of the operating medium is correspondingly increased. Good volumetric efficiency in such machines requires very precise manufacture. It has been found, for example, that the temperature differences that necessarily occur between stationary and orbiting spiral parts can have a disadvantageous effect.
In accordance with a second embodiment disclosed in the aforementioned patent, feeding of the operating medium proceeds similarly, but this embodiment is different in that rather than employing an orbiting motion of a displacement body in a stationary feed chamber, this second embodiment employs rotary motion of both intermeshing displacement bodies. This rotating spiral loader substantially comprises a housing in which is disposed two symmetrically designed displacement disks that are rotatable by means of drive elements. One of the two displacement disks is supported on a shaft journal. The second disk is secured so as to be fixed against relative rotation to a drive shaft. Rotation of the second disk causes the first disk to rotate in the same direction at the same rotary speed. Both disks execute a relative motion in the form of a circular displacement.
A machine of the type in which, unlike the above two types of machines, a plurality, in this case two, intermeshing spiral displacement bodies are disposed to orbit in a stationary housing, is generally known from German Letters Patent No. 174 074, issued as early as 1906. In this machine, however, the circular guidance of the disks which are mounted on a central drive and crankshaft and which are each equipped with one displacement body, is effected by a plurality of radially disposed outer crankshafts that are constrained in respect to one another and are supported by a rotatable frame.